1. Field of Invention
This invention relates to precast concrete components of structures and prefabricated structural reinforcement of cast in place concrete structures.
2. Description of Related Art
Precast structural concrete is commonly used by those skilled in the art to rapidly assemble buildings, roads, bridges, and other structures. Precast components and pre-fabricated structural reinforcement minimize logistical burden, cost, and assembly time of construction as compared to other conventional techniques of assembling with smaller components in the field. These components are manufactured in a factory oftentimes to higher levels of complexity than what is achievable in the field. Precast components in particular are used where a high degree of quality control, minimized assembly time on site, and highly repetitive components are necessary in the construction of a structure.
Techniques such as casting in place of structurally reinforced concrete are typically used for larger reinforced concrete structural components such as columns and slabs, and are facilitated by removable formwork and prefabricated structural reinforcement.
Under certain circumstances described herein, the logistic advantages of both cast in place concrete and precast concrete are desired. To this end, the inventors provide a novel method to assemble reinforced concrete structures using a non-removable formwork composed of structural elements and prefabricated structural reinforcement.
Prefabrication is a means of achieving high levels of quality at low cost in a mass production environment. Prefabrication allows the designer to achieve higher levels of complexity with regard to system integration, surface finish, and customization in systems and finishes. This complexity is managed in a factory environment. In addition, prefabrication of modular components allows for a variety of designs to be realized using a limited number of standard parts. Prefabrication of systems leads to cost reductions since a limited number of trade skill is present on site and the diversity of building materials at the construction site is reduced.
Cast in place reinforced concrete structures are able to achieve a high level of structural integrity at minimal cost. The features of the technique are well known to those skilled in the art, and will not be discussed here. Several notable limitations to conventional cast in place reinforced concrete exist, which the inventors have been able to overcome with the present invention. First, cast in place reinforced concrete requires the manipulation of formwork and mold components, which can be burdensome and complex for low skill labor on construction sites. Manipulating this formwork on site also entails proper placement of structural reinforcement, which again is a burden to low skill labor. Some notable examples of structural failure familiar to those skilled in the art include cases in which on site labor neglected to include structural reinforcement, leading to catastrophic failure. Further, the designer has little control over the quality of the concrete available on site, particularly with regard to construction sites in developing countries. Conventional cast in place concrete structures result in a surface finish which is dependent on the quality of the concrete on site, the surface finish and condition of the formwork, and the skill of the on-site labor, which again limits the quality attainable by conventional cast in place concrete. By utilizing a permanent leave behind prefabricated formwork with integral structural reinforcement, the present invention is able to overcome the difficulties related to structural integrity and quality due to construction site factors out of the control of the designer.
Material handling equipment typically used to place large or heavy precast components can be limited to various construction site logistics, so it is often in the interest of the designer to minimize the size or weight of a precast component to facilitate construction. Designs which are limited in the size or weight of a precast component are typically cast in place instead; however, cast in place constructions are limited in the manner discussed previously. Therefore, a lightweight construction which can offer the site logistics of a precast component and can be further cast in place for permanent placement would overcome the logistical burden of excessively large or heavy precast components as well as the quality limitations associated with cast in place concrete structures.
The need to construct concrete structures in certain developing countries is significantly complicated by the lack of available skilled labor and on site quality control measures such as inspections and testing. Many conventional precast concrete structures which are assembled on site make use of integral metal connectors such as threaded rods, joining plates, and bolts. Assembling such conventional precast concrete structures and ensuring the quality of integral connections is burdensome for low skill labor; for example, torque control fastening may not be available on site, a construction site may lack workers with the required training for installing or welding structural connections, a construction site may lack the requisite inspection capacity required for structural connections, or the proper steel finishing techniques for the structural connections may not be accessible in such developing countries. Therefore, precast components that are assembled on site to create leave in place formwork significantly benefit from designs and methods that do not incorporate such conventional metal joining plates, bolts, and the like. The present invention is able to overcome the quality limitations of these conventional components by providing novel components which are inserted into one another and subsequently filled with concrete for proper assembly without the need for conventional metal joints.
The assembly of precast components on a construction site can be optimized to enhance construction speed by minimizing the need for temporary fastening, bracing, and shoring of precast components prior to adding the concrete infill. The present invention incorporates precast column form assemblies and column closure panel assemblies that do not require the temporary fastening, strapping, and clamping provisions necessary for conventional concrete formwork. Construction speed can be further optimized by limiting the number of operations which must be completed by a crane before pouring concrete. The present invention provides components which incorporate the structural reinforcement, further enhancing construction speed.
Due to the limitations of conventional techniques described herein, the inventors have made a novel invention to overcome said limitations and result in high quality construction with minimized logistical burden and cost.